My motor requires 360 CCA, the 50# trolling motor I want requires 47 amps
(max draw). I doubt I would ever use the trolling motor more than 2 hours
at a time

You'd do well to plan 300 amps of battery for your trolling motor alone.

Sounds like a lot, but there's why:

2 hours at 47 amps = round to 100 ah.

It's best not to discharge a l/a battery below 50% of its rated capacity, so
100 X 2 = 200.

Then you have to make an allowance for the "sweet spot" in the recharge curve.
If you're discharged to 50%, the battery will
recover to 80% fairly quickly but the remaining 20% of charge to full takes
considerably longer. Unless you will always have ample recharge capability
between uses, you can only "count" on using 30% of the battery's
capacity....(that portion between the 50% floor you want to avoid discharging
below and the 80% charge state that you can recover fairly quickly. The "belt
and suspenders" approach is to take your amp hour requirement (about 100) and
multiply it by three. 3 X 30% = 90%, probably close enough for jazz.